Coating apparatus



April 7, 1942. "R. -w. HODIL arm. 2,279,166

COATING APPARATUS Filed May 8, 1940 INVENTORS I lPa/pb W Hod/7. anoQ/o/m CReoma/m' g 5 k, m 4.,

mesa relates to the m Passes s ew, 1942 uNlrso FATE Mr orrlcs 2,319,156 1 coa'mm mourns I Ralph W. Hodil and John C. ltedlnonl'l.

Ioungatown, Ohio Application May a, 1940, Serial No. starts of coating and, to the *galv'anisingor the like.

.-Inthe galvanizing of metal trade men-es sheets or strip "by the conventional hot-dip process. the level of the coating bath or molten sine at the exit rolls isoneo'f the-factors which the thickness of the coating formed ,on a the base metal. In order that the product shall be uniform in respect to the thickness of the procedure'is not adapted to 'a-close regulation of the level of the coating bath. We have J invented a'no'vel apparatus for controlling the level of the coating bathin a galvanizing apparatus. which is'eifecti've to maintain the level at the'desired pointavithin narrow limitzu'ree me or 'g'ardless of consumpflon 'oi the coating replenishment of the supply thereof, i Ina preferred "embodiment and practice of our invention, we provide; a displacement member adapted to be lowered into-the bath or lifted therefrom as may be necessary, to maintain the surface of tbe=bathat-the proper level.- We provide automatic means "responsive to the level f the bath for correctingany departures from a predetermined normal level.

The aforementioned preferred embodiment and practice of the invention are illustrated'more or less tically in the accompanying drawin: and will be described and explained in detail hereinafter, with reference thereto. In the draw rig. 1'18. a longitudinal section through a galaninng machinejincorporated our invention:

and V Pig. 2 is a transverse section therethrough taken along theplane of line II-II of Fig. 1.

. Referring now in detail to the drawing, a galvanizing pot II is provided with the usual rig ll including med side frames in which are Journaled entry rolls i2, bottom rolls II and exit rolls l4. Guides ll direct sheets emerging from a flux tank between the entry rolls. From the entry rolls the sheets are directed by guides ll between'the bottom rolls and thence by guides i1 between the exit rolls which remove excess coating material from the sheets. The several setsofrolls are moimted and driven in the customary manner.

-.While we. have shown in the drawing, by way coating ofmetal as by ,s (Cl. 91-125) of example only, a sheet gflvariihing machine, it'will be understood that the invention may also be; incorporated in strip-galvanizing apparatus.

in order to, apply the "proper coating to the sheets'traversing the pot, the level of the, molten zinc therein'should be'maintained at about the height indicated by the chainline l8. e level may be raised or lowered slightly, however,, it it is desired to vary the thickness of the coating applied. In order to'maintai'n the level of the I coating bath at a predetermined height, we probetween guides 2|,the sides 01! themembe'r bevide 'a displacement member or weight I! adapted to be immersed in the bathto a. greater or less extent. The member- I! may conveniently be of box-like formation as shown and should be of such weight as to displace the molten zinc readily. The member I! is reciprocable vertically ing rece'ssed as at 2| to receive the guides. The

guides'are secured to bridge angles 22 extending across the'pot II resting on supporting yok'esfl carried thereon.

A base plate 2|"is secured to the angles-22 and provides a support for a bearin'gcasting 25'. A'Jack screw "secured to the member l9 ex- 1 tends upwardly through the bearing casting 25 being guided for vertical movement'by spaced eyes 2! formed-therein. A- worm wheel 281s positioned-between eyes 2I ,and has a threaded bore for receiving the screw 26. I

The casting 25 is 22 for a worm shaft. 30. A worm 2| on the shaft ll meshes with the wheel 28. A motor 82 mounted onthe base plate llis-coupledto the worm shaft 22 by a coupling 22. 1

It will be understood that the operation of the motor 22 in one direction or the other will eil'ect vertical adjustment of the displacement member l2v by 'rotation of the worm wheel through which the screw 26 isrthreaded.

The motor 32 may be of anysuitable type and is provided with the necessary control equipment whereby it may be started, stoppedand reversed as desired. For purpose of illustration, however, we have shown a motor 32 as of the double field winding, series type. In'any event,

the motor is controlled by a float switch mechanism' indicated generally at 24. This mechanism comprises a pair of vertically spaced fixed contacts 35 and 28. Cooperating with these contacts is a moving contact 21 mounted on a rod 22 extending upwardly from a float 29 immersed in the bath. The rod 38 is guided for vertical movement in a bracket Ill securedto one of the yokes 23. The contact 21, furthermore, may be adalso provided with bearings justableon the rod 38 as by means of a set screw or the like.

In the drawing. contact. I] is illustrated in median positiombetween the contacts 35 and 18. It will be apparent, however, that the contact 31 will engage one or the other of the contacts I! and ll upon a sumcient departure of the level of the coating bath from the normal level It. If it is assumed, therefore, that the level of the coating metal falls, as it does in practice because of the removal of coating metal by the sheets passing through the bath, the contact 31 will ultimately engage the contact 38. This closes an energizing circuit for the motor 32 from one side of a supply line 4|, through the contacts 31 and 36 and thence'through one of the field windings of the motor 32 and its armature, in series,

thus driving the motor 32 in one direction. Connections to the motor, of course,will be so made that on engagement of the contacts 31 and 36 the motor is driven in the direction necessarv to lower the displacement member 19.

As the member I! is lowered by operation of the motor 32 as described above, the amount of molten coating metal displaced thereby is increased and the level of the metal in the tank is raised accordingly. The raising of the level of the bath lifts the float 89 and thereby causes separation of contacts 31 and 38. This termi- "nates the corrective operation for the time being.

Whenever the level of the bath falls further, however, the operation is repeated. It is necessary at intervals to replenish the supply of molten coating metal in the pot III. This may be done in the usual manner by adding solid spelter to the bath. The apparatus of our invention immediately accommodates itself to the resulting change in the level of the coating bath; Addition of fresh coating metal will naturally tend to raise the level of the bath and also the float I9. 1 As a result, the contact 31 engages the contact 85 and, in the manner already described, causes operation of the motor 32 but this time in the reverse direction. The displacement member I! is thus raised, decreasing the amount of molten metal displaced thereby and lowering the level of the bath until the'descent of the float 38 causes the contact 31 to separate from the contact 35.

It will be apparent from the foregoing description that the invention operates automatically to maintain the desired level of the coating bath at all times and immediately corrects departures from the predetermined level whether a fall resulting from consumption of the metal or a rise resulting from pouring in fresh metal. By reason of this automatic maintenance of the proper level of the metal in the pot, the material passing therethrongh is,coated to a uniform thickness. The invention also lends itself readily to controlling the thickness of the applied coating. Adjustment of the contact 8 on the float rod 3| will obviously cause cool-responding adjustment of the level of the floating metal. If it is desired to apply a'thicker coating, therefore, it is only necessary to adjust the contact 31 so that it maintains the coating metal at a 'level somewhat above that indicated at II, and vice versa. thus making it unnecessary to pour in or dip out substantial quantities of zinc in order to change the thickness of the applied coating.

The invention is simple in construction and effective in operation, requiring little or no maintenance.

Although we have illustrated and described but a'preferred embodiment and practice of the invention, it will be understood that changes in the construction and procedure disclosed may be made without departing from the spirit of the invention or the scope of the appended claims. While the invention has been described with particular reference to the galvanizing of sheets, it is also applicable to other coating operations and to other classes of material.

We claim: 7

1. Coating apparatus comprising a coating bath, a displacing member adapted to be submerged in the bath, means for varying the submergence of said member, and means actuated in accordance with changes in the level of the bath for controlling said last-mentioned means to raise or lower said displacing member.

2. Coating apparatus comprising a coating bath, a displacing member adapted to be submerged in the bath, means for varying the position oi said member vertically and means actuated in accordance with changes in the level oi the bath for controlling the last-mentioned means to raise or lower said displacing member.

3. In agalvanizing apparatus, a zinc bath, a displacing member adapted to be lowered into the bath as the zinc is consumed to maintain the level thereof at a predetermined height and to be raised as zinc is added, means for varying the position of said member, and a float switch actuated in accordance with changes in said level for controlling said means to raise or lower said displacing member.

RALPH W. HODIL JOHN C. REDMOND. 

